1. Field of the Invention
The present invention relates to a disk drive for recording data on or reproducing data from a disk such as a floppy disk or a rigid disk, and more particularly to a disk drive preferably used as an external storage of electronic apparatus such as personal computers, word processors or the like.
2. Description of the Prior Art
Disk drives carry out recording to or reproducing from disk-shaped recording media such as magnetic disks, laser disks or the like. The disk drive is constructed to perform recording to or reproducing from a disk as follows: a disk, the recording medium, is inserted into the disk drive and is ejectably loaded thereto; the disk is rotated by a driving motor; heads are made to contact or made to approach a surface of the disk; and writing data on or reading data from the disk is carried out while the heads are moving. In this case, the heads are mounted on a carriage which is moved by a driving motor, so that the heads are moved on the disk in the radial direction (seek operation). An example of the disk drive is shown in Japanese Patent Application Laying-open No. 161,680/1990 (U.S. Ser. No. 07/392,045).
The disk drive comprises, on a base that supports respective component parts of the disk drive, an installation and removal means for installing or removing the disk, a disk rotation drive means for rotating the disk by a motor, a head seek means for moving heads on the disk in the radial direction to position the heads on a target track, a head loading means for loading or unloading the head to or from the disk, and the like. In addition, there are provided a control circuit for controlling the entire disk drive, and a connector for a power supply. The control circuit is connected to a host computer system via an interface so that the control circuit receives data from and supplies data to the host computer system.
In general, the installation and removal means includes a cassette guide that supports a disk cassette in which the disk is housed, and guides the disk cassette into the disk drive so as to install it on the disk rotation drive means and guides the disk cassette out of the disk drive so as to remove it from the disk rotation drive means, a slide plate that has a cam portion which engages a part of the cassette guide to lower or raise it, and is movable in directions in which the disk cassette is installed or removed, a latch member that controls an ejection of the disk cassette in response to the movement of the slide plate. The disk drive has a shutter opening means for opening a shutter of the disk cassette by engaging the shutter in accordance with the installation of the disk cassette. The shutter opening means has an arrangement such that the latch member functions also as an engaging member which engages the shutter, or alternatively, an arrangement in which is used a shutter lever having an engaging member that is rotatably supported on the cassette guide and can engage the shutter.
The aforementioned components of the disk drive are housed in the base which is shaped like a box, the opening of which is covered by a cover for forming a dustproof and magnetic shield.
When such disk drives are used as external storage for electronic apparatus such as personal computers or word processors, they are sometimes constructed as independent apparatus. In general, however, they are incorporated into the main bodies of the electronic apparatus. As the electronic apparatus are reduced in size and increased in portability, a reduction in size and weight and an increase in the portability of the disk drives are increasingly required.
In the conventional disk drive, at an upright portion, is provided a cam portion of a slide plate. The upright portion overlaps an outer surface of a side wall of the cassette guide. As a result, the base for housing the components of the disk drive needs extra space for the overlapping of the upright portion with the outer surface of the side wall of the cassette guide. This presents a problem in that the width of the disk drive becomes large, and hence it is hard for the disk drive to be made small. Additionally, in the conventional disk drive, a cam mechanism for raising or lowering the cassette guide is disposed in substantially the same horizontal plane in which the disk cassette is placed. With this arrangement, it is also hard for the disk drive to be made small.
Further, in the head loading means used in the conventional disk drive, the head is attached to the head arm which is rotatable around a fulcrum on the carriage. As a result, when the head is unloaded upon ejection, the head arm is elevated approximately linearly at an angle starting from the fulcrum. This causes a problem in that the tip portion of the head arm reaches a considerable height when the head arm is elevated, or in that the height of an upper end of a head unit including the head arm becomes considerably large, which requires an increase in the height of the inner space of the disk drive and accordingly an increase in the thickness or height of the disk drive in order to eliminate contact between the head unit and the inside of the disk drive.
A proposal could be made to attach the head arm to the carriage through a leaf spring or the like in order to decrease the angle of inclination of the head arm to be as small as possible or until the head arm becomes horizontal giving the advantage of a deflection effect of the leaf spring. However, this would be insufficient since the use of the leaf spring alone for supporting the head arm is based fundamentally on swinging action. Hence not only the height of the tip of the head arm must necessarily be larger in order to keep a predetermined gap between the head and the inner surface of the case of the disk drive, but also it becomes difficult to stably control the height and angle of the tip of the head arm. As a result, the uppermost position of the head unit at its highest portion is also unstable. Therefore, it is necessary to set up the height of the disk drive to a sufficiently large value with allowance, which is contradictory to the compactness of the disk drive.
A conventional approach could be adopted in which the head arm is attached to the carriage through a leaf spring or the like, and a stopper for controlling the uppermost height of the head arm is provided. However, the provision of such a stopper results in the production of an abrasion dust due to frictional sliding between the head arm and the stopper as a result of movement (seeking) of the head unit which occurs even in a head unloaded state (in a raised state). The dust invades the inside of the disk cassette through its head accepting aperture to cause the possibility of damaging the recording medium held in the disk cassette.
In addition, in the conventional disk drive, a cover of a uniform thickness is fitted on an open end of the base, which inevitably increases the thickness or height of the disk drive by the thickness of the cover itself. This not only makes it difficult to make for compactness of the disk drive but also gives rise to the possibility of causing distortion in the base because the cover should be detached every time inspection of the inside, or exchange or adjustment of the parts of the disk drive is performed. As a result, adverse influences on the reliance of the disk drive could result and it would be troublesome to perform such an adjustment or the like.